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New rat genus discovered in the birthplace of the theory of evolution

New rat genus

A prominent tuft of spiny hair on the back, a white tail tip and three pairs of teats represent the unique set of characteristics describing a new genus of rat which has been discovered in the Moluccan province of Indonesia. This region had a profound influence on the British Naturalist Alfred Russell Wallace who independently developed the theory of evolution alongside Charles Darwin. The international team of zoologists was led by the Museum Zoologicum Bogoriense in Indonesia and the Center for Macroecology, Evolution and Climate at the University of Copenhagen

One hundred years after the death of Sir Alfred Russel Wallace, an international team of zoologists has discovered a new genus of mammal in the Halmahera Island in Indonesia. It is located in Wallacea, an Eastern Indonesian region named after the British Naturalist himself. The team was surprised to find the new endemic rodent close to the locality of Boki Mekot, a mountainous area under severe ecological threat due to mining and deforestation.

“This new rodent highlights the large amount of unknown biodiversity in this Wallacean region and the importance of its conservation. It constitutes a valuable addition to our knowledge of the Wallacean biodiversity and much remains to be learned about mammalian biodiversity across this region. Zoologists must continue to explore this area in order to discover and describe new species in this highly diverse, but also threatened region.”

Halmaheramys bokimekot is a terrestrial spiny rat of medium body size with brownish grey fur on its back and a greyish white belly. Together with its other characteristics it represents a unique set of features that has never been reported before in the Moluccas.

The region that inspired Wallace

It is clear that the region had a profound influence of Wallace’s thinking as it was from the Moluccan province of Indonesia that Wallace wrote his famous letter about natural selection and evolutionary theory to Charles Darwin. The two naturalists both published their findings in 1858.

The unique nature of the plants and animals found within the region and the large floral and faunal differences to the neighboring region of Australia, later inspired Wallace to define a zoogeographical boundary dividing the Indonesian archipelago into two distinct parts: a western portion in which the animals are largely of Asian origin and an eastern portion where the fauna reflect Australasia. This is known as the Wallace line.

New rat reveals a rare migration event

“The Halmaheramys discovery supports Wallace’s idea of an important faunal breakup in this region. Most of the species on the island of Halmahera reflect eastern origins, but our genetic analysis revealed a western origin of the new rat genus. That reflects the unique transition zone found in the Indo-Pacific, and warrants much greater scientific investigation,” says Pierre-Henri Fabre.

“Such a remarkable island setting inspired one of the greatest biologists of all time, and if Sir Alfred Russell Wallace were alive today he would surely be excited by the prospect of further conservation and biodiversity study within the Moluccas,” says Pierre-Henri Fabre.

Photo: Pierre Henri Fabre

The team’s findings are published in the Zoological Journal of the Linnean society: